The NIH-funded (P30 AR046121) Musculoskeletal Repair and Regeneration Core Center (MRRCC) at the Hospital for Special Surgery must replace its EVS/GE micro-computed tomography (micro-CT) system because GE will no longer have parts available for the prototype model we have been using for the past ~7yrs. The purpose of this application is to acquire a new micro-CT to speed data acquisition time, decrease the time users wait to collect data, and eliminate the down time we now experience as parts are scavenged to repair the current unit. The Core Center currently has a research base of 20 NIH funded investigators working in the area of bone development and repair. Additionally, outside users from Columbia University, New York University (NYU), City College of NY, and Weill Medical College of Cornell University utilize the micro-CT services provided by the MRRCC Imaging Core (also including imaging technologies beyond micro-CT). For these investigators, skeletal integrity, as defined by the biological, chemical, and mechanical influences that make bone such a distinctive tissue, is a fundamental part of their research. By applying advances in molecular biology and genetics, these researchers are integrating biology and engineering into in vivo experiments using small animal models to examine the relation between composition, structure, and function that allows the skeleton to fulfill its unique role. The replacement micro-CT system will provide crucial detailed structural information on the small bones and teeth from these animals that will complement analysis provided through other MRRCC cores, such as compositional measurements (from infrared imaging) and functional data (from mechanical testing and finite element analyses). The micro-CT system is currently being used by 20 MRRCC investigators (with 28 funded projects) including novel studies of cartilage properties, angiogenesis, and tooth development, in addition to frequent evaluations of mouse phenotype and human bone properties. The grant for the micro-CT system will be administered within the MRRCC. Because this instrument is a replacement, policies and procedures are in place for its use, prioritization, maintenance, and oversight, and experienced technical staff are available for training and data processing. The studies performed on the micro-CT are providing novel quantitative 3D information on the effects of a variety of genetic manipulations on skeletal integrity and on the effects of therapeutics on the musculoskeletal system. [unreadable] [unreadable] [unreadable] [unreadable]